[Discuss] Migrating hundreds of mbox files to an IMAP server?

[Dan Ritter]

Rich Pieri wrote: 
> On Mon, 2 Jun 2025 07:32:30 -0700
> Kent Borg <kentborg at borg.org> wrote:
> 
> > I've tried copying a big offline Thunderbird mailbox to a live
> > Dovecot server, and it worked for the first 11,880 messages, but now
> > won't do any more. I know Dovecot can handle more because this came
> > from an earlier instance of Dovecot.
> 
> Dovecot can handle tens (maybe hundreds) of thousands of messages in a
> mail folder. You don't specify which backend Dovecot is using: mbox or
> Maildir. If you're using mbox then you may be hitting a timeout:
> scanning the the mbox file takes longer than the server-side connection
> timeout.

I had a user with over a million messages in a single
Dovecot-accessed maildir.

Eventually I persuaded them to let me break it down by year into
separate Maildirs...

-dsr-